﻿using System.Diagnostics.Contracts;
using System.Linq.Expressions;
using System.Reactive.Concurrency;

namespace System.Reactive.Linq
{
	public static partial class Qbservable
	{
		public static IQbservable<TSource> ElementAt<TSource>(this IQbservable<TSource> source, int index)
		{
			Contract.Requires(source != null, null, "source != null");
			Contract.Ensures(Contract.Result<IQbservable<TSource>>() != null, null, "Contract.Result<IQbservable<TSource>>() != null");
			return null;
		}

		public static IQbservable<TSource> ElementAtOrDefault<TSource>(this IQbservable<TSource> source, int index)
		{
			Contract.Requires(source != null, null, "source != null");
			Contract.Ensures(Contract.Result<IQbservable<TSource>>() != null, null, "Contract.Result<IQbservable<TSource>>() != null");
			return null;
		}

		public static IQbservable<TResult> Empty<TResult>(this IQbservableProvider provider)
		{
			Contract.Requires(provider != null, null, "provider != null");
			Contract.Ensures(Contract.Result<IQbservable<TResult>>() != null, null, "Contract.Result<IQbservable<TResult>>() != null");
			return null;
		}

		public static IQbservable<TResult> Empty<TResult>(this IQbservableProvider provider, IScheduler scheduler)
		{
			Contract.Requires(provider != null, null, "provider != null");
			Contract.Requires(scheduler != null, null, "scheduler != null");
			Contract.Ensures(Contract.Result<IQbservable<TResult>>() != null, null, "Contract.Result<IQbservable<TResult>>() != null");
			return null;
		}

		public static IQbservable<TSource> Expand<TSource>(this IQbservable<TSource> source, Expression<Func<TSource, IObservable<TSource>>> selector)
		{
			Contract.Requires(source != null, null, "source != null");
			Contract.Requires(selector != null, null, "selector != null");
			Contract.Ensures(Contract.Result<IQbservable<TSource>>() != null, null, "Contract.Result<IQbservable<TSource>>() != null");
			return null;
		}

		public static IQbservable<TSource> Expand<TSource>(this IQbservable<TSource> source, Expression<Func<TSource, IObservable<TSource>>> selector, IScheduler scheduler)
		{
			Contract.Requires(source != null, null, "source != null");
			Contract.Requires(selector != null, null, "selector != null");
			Contract.Requires(scheduler != null, null, "scheduler != null");
			Contract.Ensures(Contract.Result<IQbservable<TSource>>() != null, null, "Contract.Result<IQbservable<TSource>>() != null");
			return null;
		}
	}
}